The objective of the Electrophysiology and Xenopus Oocyte is to make readily available to Toxicology Center investigators a variety of electrophysiological assays for ion transport and the Xenopus oocyte expression system for transporters and receptors. The rationale for establishing the core is that these techniques require specialized equipment and/or expertise that might not be available otherwise. The core will offer a broad range of assays ranging from flat-sheet, Ussing Chamber Studies to single channel recording and analysis. In addition the core will be equipped to harvest, defolliculate and inject, with RNA, Xenopus oocytes that can be used as an expression system for transporters or receptors. A primary aim of the Center for Membrane Toxicity Studies is to investigate the mechanism for the toxic effects of metals on membrane proteins, transporters and receptors. The Electrophysiology and Xenopus Oocyte Core will provide the equipment and expertise for Center investigators who wish to employ these important technologies in their research.